Speech recognition is hampered by background noise present in the input signal. To reduce the effects of background noise, efforts have been made to determine when an input signal contains noisy speech and when it contains just noise. For segments that contain only noise, speech recognition is not performed and as a result recognition accuracy improves since the recognizer does not attempt to provide output words based on background noise. Identifying portions of a signal that contain speech is known as voice activity detection (VAD) and involves finding the starting point and the ending point of speech in the audio signal.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.